U.S. patent number 7,287,825 [Application Number 11/150,113] was granted by the patent office on 2007-10-30 for preliminary ejection method and ink jet printing apparatus.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Naoko Baba, Tomomi Furuichi, Daigoro Kanematsu, Mitsutoshi Nagamura, Kazuo Suzuki, Rie Takekoshi.
United States Patent |
7,287,825 |
Furuichi , et al. |
October 30, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
Preliminary ejection method and ink jet printing apparatus
Abstract
In an ink jet printer in which preliminary ejection is performed
onto printing paper, unnecessary ink consumption due to the
preliminary ejection is suppressed. More specifically, the paper
preliminary ejection is designed to be performed only for a
printing head of cyan ink. For this cyan ink the longest duration
of its non-ejection state, in which the printer can attain high
printing quality when restarting printing after continuation of the
non-ejection state in the case of not performing the paper
preliminary ejection, is shorter than 1.6 seconds of the duration
which is necessary for the reciprocal printing. This eliminates the
paper preliminary ejection for the printing heads of the other
colors of ink, thereby avoiding unnecessary ink consumption due to
the paper preliminary ejection performed uniformly for every color
of ink.
Inventors: |
Furuichi; Tomomi (Yokohama,
JP), Takekoshi; Rie (Kawasaki, JP),
Kanematsu; Daigoro (Yokohama, JP), Baba; Naoko
(Kawasaki, JP), Suzuki; Kazuo (Yokohama,
JP), Nagamura; Mitsutoshi (Tokyo, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
35460067 |
Appl.
No.: |
11/150,113 |
Filed: |
June 13, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050275683 A1 |
Dec 15, 2005 |
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Foreign Application Priority Data
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Jun 15, 2004 [JP] |
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2004-177374 |
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Current U.S.
Class: |
347/24; 347/19;
347/23 |
Current CPC
Class: |
B41J
2/16526 (20130101) |
Current International
Class: |
B41J
2/165 (20060101) |
Field of
Search: |
;347/24,30,35,23,19,5,9 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Nguyen; Lam Son
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A paper preliminary ejection method, which is used in an ink jet
printing apparatus in which ink is ejected from a printing head for
ejecting a plurality of kinds of ink to a printing medium to print
an image, for performing ink ejection, unrelated to the image to be
printed, on the printing medium, said method comprising: a step
for, for each of the plurality of kinds of ink, determining
information on predetermined time periods for each of a plurality
of frequencies for paper preliminary ejection including a lowest
frequency at which no paper preliminary ejection is performed, each
predetermined time period being defined as a time period elapsing
after an operation of discharging ink from the printing head with
the paper preliminary ejection being performed at the corresponding
frequency, wherein after the predetermined time period having been
elapsed and upon starting of printing a predetermined image, no
predetermined degradation of printed image occurs; and a step for,
for each of the plurality of kinds of ink, comparing the
predetermined time period for each of the plurality of frequencies
with a time period from the operation of discharging ink to the
next operation of discharging ink, and when the predetermined time
period is shorter than the time period from the operation of
discharging ink to the next operation of discharging ink,
performing the paper preliminary ejection at a frequency higher
than a frequency corresponding to the predetermined time period for
the corresponding ink.
2. A paper preliminary ejection method as claimed in claim 1,
wherein the frequency for the ink corresponding to the
predetermined time period which is shorter than the time period
from the operation of discharging ink to the next operation of
discharging ink is the lowest frequency.
3. A paper preliminary ejection method as claimed in claim 1,
wherein the frequency for the ink corresponding to the
predetermined time period which is shorter than the time period
from the operation of discharging ink to the next operation of
discharging ink is a frequency higher than the lowest frequency.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet printing method and an
ink jet printing apparatus and, more particularly, to an ink jet
printing method and an ink jet printing apparatus for performing
so-called preliminary ejection, in which ink is ejected from a
printing head unrelated to printing, while printing an image.
Also, the present invention can be applied to apparatuses such as a
printer, a copying machine, a facsimile machine having a
communication system, a word processor having a printer section and
so on for printing on a medium to be printed such as paper, yarn,
fiber, fabric, metal, plastic, rubber, glass, wood, ceramics and so
on and, moreover, industrial printing apparatuses combined
complexly with various processing units.
It should be appreciated that "printing" in the present
specification means not only to afford images having a meaning such
as characters and graphics to the medium to be printed, but also to
afford images having no meaning such as patterns.
2. Detailed Description of the Related Art
The preliminary ejection is performed to discharge highly viscous
ink and dust in an ink ejection orifice of a printing head through
ink ejection thereof so as to keep the ejection performance of a
printing head satisfactory. It is also executed for avoiding
density unevenness on a printed image by ejecting ink whose
concentration of color material such as dye and pigment has
increased. A usual manner of such preliminary ejection is that, in
the case of serial method of printing by causing the printing head
to scan, the ink ejection is performed, for the preliminary
ejection, to an ink receptacle disposed at one end of the scanning
area. Further, in the case of full line method for printing by
moving a printing medium with respect to a printing head whose ink
ejection orifices are arranged in correspondence to the width of
the printing medium, the ink receptacle is moved relatvely to the
printing head to oppose thereto and ink is ejected to the same.
On the other hand, those of which ink is ejected for the
preliminary ejection while an image is printed on the printing
medium are also known. For instance, it is described to perform the
preliminary ejection at a constant frequency for the Ink ejection
for printing, in Japanese Patent Application Laid-Open No.
1980-139269. According to such preliminary ejection, it is not
necessary for the printing head to move for preliminary ejection as
in the case of performing the preliminary ejection to a
predetermined ink receptacle disposed in the printer. Therefore, it
becomes possible to prevent the throughput of printing from
lowering as much. Even when the ejection is not performed for
certain ejection orifices during the printing in relation with the
printing data, the preliminary ejection can be performed for these
ejection orifices, because this method for performing the
preliminary ejection to the printing medium (also referred as
"paper preliminary ejection" in the present specification) is
performed, basically, with accompanying the ink ejection for
printing an image. More specifically, during the printing, the
printing is performed in a state where the printing head is not
covered with a cap or the like and the ejection orifice part is
exposed, and in this case, even when the ejection is not performed
for certain ejection orifices according to the printing data, the
ink ejection through preliminary ejection can be performed for
these ejection orifices, allowing to effectively prevent ejection
failure due to the exposed state.
Particularly, the paper preliminary ejection is effective in the
case of printing on a relatively large sized printing medium. More
specifically, in the case of printing on a large sized printing
medium, the throughput tends to lower because as much time is
necessary for the printing head to scan. However, the paper
preliminary ejection can partly replace normal preliminary
ejection, which is performed at a predetermined position in a
printing apparatus, or can be performed in place of the normal
preliminary ejection. Thereby, time period for the normal
preliminary ejection can be decreased as much and thus lowering of
the throughput can be prevented. In addition, on focusing attention
on an ejection orifice in the printing head, a non-ejection state
of the ejection orifice, for which print data represents
"non-ejection", may continue, and then ink ejection from the
ejection orifice may be executed by that the print data represents
"ejection" during scanning of the printing head in the non-ejection
state. In such case, when printing on a large sized printing
medium, the ejection orifice in the printing head remains exposed
for a long period of time. For this condition, the paper
preliminary ejection is performed and then first ejection for
printing after the exposed state can be well executed.
However, when the paper preliminary ejection is performed for
different colors of inks without variation, unnecessary preliminary
ejection may be performed and ink may be used wastefully. More
specifically, a property of ink affecting ink ejection by the
printing head, such as a degree of viscosity increasing of ink,
generally depends on colors of ink. In such case, when the paper
preliminary ejection of a constant period is performed for a
plurality of colors of inks without variations, the paper
preliminary ejection for the ink which does not increase viscosity
during such constant period is also performed, and then the ink as
much is used wastefully.
Particularly in the case of using both the normal preliminary
ejection which is performed at a predetermined location in a
printing apparatus and the paper preliminary ejection, there may be
a case that depending on a color of ink, an ejection performance of
a printing head for ejecting the color of ink can be maintained
well only by the normal preliminary ejection. In this case, it is
desirable that the paper preliminary ejection for the color of ink
is not performed in terms of decreasing ink use for the preliminary
ejection. A reason that properties of inks, such as viscosity
increasing, affecting ink ejection by the printing head differ
depending on colors of ink is that the properties differ depending
on color materials in ink such as dye and pigment, and contents of
the color materials of the same color inks, and further differ
depending on other solvent in ink.
Further, the above discussion is the case with ejection amounts
different for each printing head. Generally, the greater an amount
(a volume of an ink droplet) of one time ejection is, the longer
the time period during which a factor causing a ejection failure,
such as increasing of ink viscosity, does not occur. Therefore,
when the paper preliminary ejection of the constant period is
performed for the plurality of colors of ink without variations,
ink may be used wastefully for the printing head ejecting such
greater amount of ink.
SUMMARY OF THE INVENTION
The present invention can provide a preliminary ejection method and
an ink jet printing apparatus which can perform paper preliminary
ejection in which unnecessary ink use is suppressed.
In a first aspect of the present invention, there is provided a
paper preliminary ejection method, which is used in an ink jet
printing apparatus in which ink is ejected from a printing head for
ejecting a plurality of kinds of ink to a printing medium to print
an image, for performing ink ejection of no concern to the image to
be printed to the printing medium, the method comprising:
step for ejecting ink to the printing medium based on image data
corresponding to the image to be printed to print the an image;
and
step for causing the printing head to execute preliminary ejection
to the printing medium, based on conditions related to the
preliminary ejection,
wherein the conditions are individually determined for respective
kinds of ink, and
the conditions are different between a kind of ink and other kind
of ink within the plurality of kinds of ink.
In a second aspect of the present invention, there is provided a
paper preliminary ejection method, which is used in an ink jet
printing apparatus in which ink is ejected from a printing head for
ejecting a plurality of kinds of ink to a printing medium to print
an image, for performing ink ejection of no concern to the image to
be printed to the printing medium, the method comprising:
step for, for each of the plurality of kinds of ink, determining
information on predetermined time periods for each of plurality of
frequencies for paper preliminary ejection including a lowest
frequency at which no paper preliminary ejection is performed, the
predetermined time period being defined as a time period elapsing
after an operation of discharging ink from the printing head with
the paper preliminary ejection being performed at the corresponding
frequency, after the time period having been elapsed and upon
starting of printing a predetermined image, no predetermined
degradation of printed image occurring: and
step for, for each of the plurality of kinds of ink, comparing the
predetermined time period for each of the plurality of frequencies
with a time period from the operation of discharging ink to the
next operation of discharging ink, and when the predetermined time
period is shorter than the time period from the operation of
discharging ink to the next operation of discharging ink, the
performing the paper preliminary ejection at the frequency higher
than the frequency corresponding to the predetermined time period
for the corresponding ink.
In a third aspect of the present invention, there is provided an
ink jet printing apparatus in which ink is ejected from a printing
head for ejecting a plurality of kinds of ink to a printing medium
to print an image, the apparatus comprising:
means for performing a preliminary ejection based on conditions
related to the preliminary ejection that ejects ink of no concern
to the image to be printed to the printing medium,
wherein the conditions are individually determined for respective
kinds of ink, and
the conditions are different between a first ink and a second ink
within the plurality of kinds of ink.
According to the present invention, conditions for paper
preliminary ejection are individually set for plurality kinds of
ink. Thereby, minimum amount of paper preliminary ejection can be
performed for each of the plurality of kinds of ink.
As a result, the paper preliminary ejection in which unnecessary
ink use is suppressed can be performed.
The above and other objects, effects, features and advantages of
the present invention will become more apparent from the following
description of embodiments thereof taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exterior perspective view showing a schematic
composition of an ink jet printer according to one embodiment of
the present invention;
FIG. 2 is a perspective view showing in detail a composition of
vicinity of the carriage in the ink jet printer shown in FIG.
1;
FIG. 3 is a diagram showing the printing head of FIG. 2 viewed from
the ejection orifice side;
FIG. 4 is a block diagram showing a configuration of the control
system in the ink jet printer of the present embodiment;
FIG. 5 is a diagram illustrating data processing in the host device
200 and the printer 240 mentioned in FIG. 4;
FIG. 6 is a diagram illustrating an index development shown in FIG.
5;
FIG. 7 is a diagram showing the printing data for paper preliminary
ejection added in the embodiment of the present invention, through
a pattern of pixel arrangement;
FIG. 8 is diagram especially illustrating time period from a normal
preliminary ejection to the next normal preliminary ejection in a
printing operation according to an embodiment of the present
invention;
FIG. 9 is a diagram showing ejection orifice arrangement according
to a third embodiment of the present invention;
FIG. 10 is a block diagram showing a data processing in the host
device 200 and the printer 240, in the case of adding preliminary
ejection data of the index form, according to another embodiment of
the present invention;
FIG. 11 is a diagram illustrating an index development pattern used
for the preliminary ejection; and
FIG. 12 is a block diagram showing an example of configuration of
image processing by a printer driver of the host device, according
to still another embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Embodiments of the present invention will be described in detail
referring to accompanying drawings. A printer shall be illustrated
as an ink jet printing apparatus, in the embodiments described
below.
FIG. 1 is an exterior perspective view showing a schematic
composition of an ink jet printer according to one embodiment of
the present invention. As illustrated, in the printer, a printing
head scans a printing medium through back-and-forth motion (this
moving direction is refeffed as "main scanning direction") of a
carriage 11 detachably mounting a head cartridge integrating the
printing head and an ink tank for storing ink. During this
scanning, the printing is performed by ejecting ink on a printing
medium such as printing paper. A carriage motor 12 constitutes a
driving source for moving the above carriage 11, and the driving
force thereof is transmitted to the carriage via a belt 4 and
pulleys 5a, 5b. A guide shaft 6 guides and supports the carriage 11
when it moves in the main scanning direction. An ejection signal or
the like for ink ejection by the printing head is transferred to
the printing head as an electric signal from a control section
mentioned below in FIG. 4, through a flexible cable 13. A cap 141
and a wiper blade 143 perform capping and wiping of the printing
head, respectively, and they are used for ejection recovery
operation. A cassette 15 stocks printing medium (for instance,
printing paper) in a layered state, while an encoder sensor 16 and
an encoder film read optically the moving position of the carriage
11.
FIG. 2 is a perspective view showing in detail a composition of a
vicinity of the carriage in the ink jet printer shown in FIG. 1. In
FIG. 2, the printing head 22 is composed integrally with the ink
tank as mentioned above, and mounted detachably on the carriage 11
in the present embodiment. There, this printing head 22 is composed
of six printing heads 22K, 22C, 22M, 22Y, 22LC and 22LM ejecting
six inks respectively in total including black (K), dark cyan (C),
dark magenta (M) and yellow (Y) as well as light cyan (LC) and
light magenta (LM) of lower colorant concentration than dark inks
mentioned above. The ink tank 21 is composed of six ink tanks 21K,
21LC, 21C, 21LM, 21M, 21Y for storing ink to be fed to the
respective printing heads 22K, 22LC, 22C, 22LM, 22M, 22Y. And, the
respective printing heads and ink tanks are formed integrally for
each ink of their corresponding colors to compose a head cartridge.
Caps 141, corresponding to six colors of inks, are disposed at the
home position in the vicinity of one end of the moving range of the
carriage 11 equipped with these cartridges. More specifically, the
cap is composed of six caps 141K, 141LC, 141C, 141LM, 141M and 141Y
so as to cover respective ink ejection faces of the six printing
heads. It should be appreciated that these reference numbers given
to respective elements are used for referring separately to these
printing heads or ink tanks, and collective reference numbers such
as "22" for the printing head, "21" for the ink tank and "141" for
the cap are used where they are referred to collectively. It goes
without saying that the printing head and the ink tank may also be
detachable individually with respect to the carriage, though they
are composed of an integral head cartridge in the aforementioned
example.
FIG. 3 is a diagram showing the printing head 22 viewed from the
ejection orifice side. As shown in FIG. 3, printing heads 22K,
22LC, 22C, 22LM, 22M, 22Y have 1280 ejection orifices disposed
approximately orthogonal to the main scanning direction with a
density of 1200 dpi respectively. These six printing heads are
mounted on the carriage 11 in a way to be arranged in the main
scanning direction. Ink amount of about 4 ng is ejected at one time
of ejection from each of ejection orifices 23.
The printing operation of the ink jet printer of the present
embodiment described above referring to FIG. 1 to FIG. 3 is
generally as follows.
When printing starts, printing papers 1 stacked in the cassette 15
are fed one by one to a printing area by a paper feed roller (not
shown). Then, the printing head 22 scans in the printing area, and
the printing paper is fed by a predetermined amount by a pair of
transport rollers 3, on a platen (not shown) installed in an area
to which the printing head 22 faces. On the other hand, ink is fed
from the ink tank 21 to the printing head 22 and the printing head
22 ejects the ink on the printing paper 1 based on printing data,
while scanning in the arrow B direction (forth scanning direction)
of FIG. 2 to perform printing in a width corresponding to a
predetermined number of ejection orifices of the printing head 22.
Ink ejection in this printing is performed by driving the printing
head according to the read timing of the encoder 16. Then, when the
printing corresponding to one scan in the arrow B direction (forth
scanning direction) is completed, the printing head 22 returns to
the original home position and prints again in the arrow B
direction (forth scanning direction). After the completion of one
printing operation (one scan) in one direction, the printing paper
1 is fed in the arrow A direction by the predetermined amount which
is the width corresponding to the predetermined number of the
aforementioned ejection orifices by driving the pair of transport
rollers 3, before the next printing operation starts. An image is
printed on the printing paper 1 by repeating the printing operation
of one scan and the feeding the paper by the predetermined amount
in this manner.
The printing head 22 returns to the home position at a
predetermined timing such as that before starting the printing, and
performs a recovery operation by a recovery mechanism. More
specifically, the ejection orifice face of the printing head 22 is
capped with the cap 141 and ink in the ejection orifice 23 is
sucked. Also, the above capping is performed during the
non-printing, to prevent the ink from drying. Moreover, a wiper
blade 143 wipes the ejection orifice 23 face of the printing head
22 by moving in the arrow C direction, to remove the ink attached
to the ejection orifice face.
Further, as described later for FIG. 7, paper preliminary ejection,
for ejecting ink on the printing paper along with the printing
operation is performed as preliminary ejection in the embodiment of
the present invention. Moreover, an ink receptacle is installed at
a position adjacent to the home position in order to perform the
preliminary ejection before starting the printing and so on in the
present embodiment, and the preliminary ejection is performed at a
predetermined timing such as that before the printing start.
FIG. 4 is a block diagram showing a configuration of the control
system of the ink jet printer of the present embodiment described
above. In FIG. 4, an image controller 210 notifies a print engine
control section 220 of a control command according to the
processing command signal from a host device 200 or an operation
section of a printer (not shown). Moreover, during the printing,
printing data received from the host device 200 is analyzed,
developed and converted into binary image data for respective
colors. The print engine control section 220 performs the printing
operation based on the control command and the image data sent from
the image controller 210. The image controller 210 and the print
engine control section 220 are connected by a dedicated interface,
allowing to perform a communication comprising the command
transmission for notifying a control command from the image
controller 210 to the print engine control section 220 and the
status transmission for informing of the state variation of the
image controller 210 from the print engine control section 220, and
the image data transfer from the image controller 210 to the print
engine control section control section 220.
In the print engine control section 220, an MPU (Micro Processor
Unit) 221 executes various operations, according to programs stored
in a ROM 227. A RAM 228 serves as a working area and a temporary
data storage area of the MPU 221. The MPU 221 controls a carriage
driving system 223, a feed drive system 224, a recovery drive
system 225 and a head drive system 226 via an ASIC (Application
Specific Integrated Circuit) 222. Also, the MPU 221 is designed to
read from and write to a print buffer 229 and a mask buffer 230
that can be read and written from the ASIC 222.
The print buffer 229 temporarily stores those image data converted
into a format to be transferred to the printing head. The mask
buffer 230 temporarily holds a predetermined mask pattern for
exerting the AND processing to the data as necessary for multi-path
printing when transferring from the print buffer 229 during the
transfer to the printing head. It should be appreciated that
several sets of mask patterns are available in the ROM 227 for
multi-path printing different in the number of paths, a concerned
mask pattern is read out from the ROM 227 during the actual
printing, to be stored in the mask buffer 230. The AND processing
with the mask buffer 229 is composed not to be executed when
unnecessary as in the case of a single path printing.
In the aforementioned composition, the printing operation starts
when image data are sent from the host device 200 to the image
controller 210. The image controller 210 analyzes the image data
received from the host device 200, generates printing quality,
margin information or other information necessary for printing and
moreover analyzes and develops the image data for starting the
conversion into the binary image data of respective colors. Along
with the development processing of these image data, information
necessary for printing by the print engine control section 220 such
as printing quality and margin information is transmitted to the
print engine control section 220. Then, in the print engine control
section 220, this transmitted information is processed by the MPU
221 via the ASIC 222 and held by the RAM 228. Thereafter, this
information is referred to as necessary and used for segmenting the
process. Furthermore, the mask pattern is written in the mask
buffer 230 as necessary.
When the notification of necessary information is terminated, the
image controller 210 starts to transfer the binary printing data of
respective colors converted from the image data to the print engine
control section 220. The print engine control section 220 writes
the transferred printing data in the print buffer 229. And, as will
be described later in FIG. 7, the OR (logical sum) of these written
printing data and preliminary generated data for paper preliminary
ejection is obtained to generate new printing data. The paper
preliminary ejection can be performed during the printing, by
printing based on the printing data to which these preliminary
ejection data are added. Printing data to be transferred to the
printing head is held successively in the print buffer 229 of the
print engine control section 220, by repeating such printing data
transfer from the image controller 210.
When the printing of data held in the print buffer 229 attains such
a quantity that allows printing of the actual band data, the MPU
221 transports the paper by the carrying drive system 224 via the
ASIC 222 and, at the same time, moves the carriage 11 by the
carriage driving system 223. Also, the recovery system is driven by
the recovery drive system 225 for performing the recovery operation
necessary before the printing operation. Furthermore, image output
position and others are set for the ASIC 222 and the carriage 11 is
driven to start the printing operation. When the carriage 11 moves
and attains the printing start position set in the ASIC 222,
printing data to which the aforementioned paper preliminary
ejection pattern is added are read consecutively from the print
buffer 229, in accordance with the ejection timing. Corresponding
mask patterns are read from the mask buffer 230 as necessary. Then
the AND (logical product) of the printing data read out and the
mask data is determined and transferred to the printing head. In
the printing head, the ejection is performed by driving the
printing head according to the transferred data, under the control
of the head driving system 226. Thus, for instance, a printing of
one page is performed by repeating the processing of receiving the
printing data from the image controller 210 and thereafter
performing the printing process for each band.
FIG. 5 is a diagram illustrating data processing in the host device
200 and the printer 240 described above in FIG. 4.
A printer driver 250, software for controlling the printer, is
preliminary installed in the host device 200, and activated when a
user intends to print a desired image. First, the printer driver
250 generates multi-value image data (here, respectively 8 bits) in
RGB (red, green, blue) or KCMY (black, cyan, magenta, yellow)
format of 600 dpi.times.600 dpi and transfers them to the printer.
If the received image data are of RGB format, the image controller
210 performs a color conversion processing 500 from RGB to R'G'B'
in order to render a color space appropriate for the printer. Next,
a color separating processing 510 is performed respectively from
8-bit data of R'G'B' to multi-value data (here, respectively 8
bits) of K, LC, LM, C, M, Y of 600 dpi.times.600 dpi for adapting
to the ink color used by the printer. On the other hand, if data
received by the image controller 210 are of KCMY format, a color
separating processing 510 is performed without performing the color
conversion processing 500. Thus, respective color data
corresponding to the ink color to be used by the printer is
generated in the color conversion processing 500 independently of
the data format generated by the printer driver 250. Colors are
converted by means of a look-up table for a predetermined color
conversion, in the color conversion processing 500 and the color
separating processing 510. The look-up table may be held
preliminary in ROM data in a printer main body, and the processing
may also be executed based on the table transferred from the host
device 200 with the printing data.
Following this, a quantization processing 520 from 8-bit (255
gradation values) data of K, LC, LM, C, M, Y to 4-bit (5 gradation
values) for respective colors is performed. The quantization
processing 520 is performed by using publicly known error
dispersion method or dither method. The 4-bit (5 gradation values)
data of quantized K, LC, LM, C, M, Y is submitted to an index
development processing 530 mentioned below in FIG. 6, and converted
into printing data of 1-bit (2 gradation values) for respective
colors of K, LC, LM, C, M, Y. The converted printing data are
transferred to the print engine control section 220.
FIG. 6 is a diagram illustrating the index development described
above. In general, the index development has an object to reduce
the processing load in the RGB multi-value data phase and, at the
same time, improve the graduation and, thereby, permits to assure
the compatibility of processing speed and image quality In the
present embodiment, the image controller 210 submits 4 bit (5
gradation values) data of 600 dpi to the index development to
obtain 1-bit (2 gradation values) data of 1200 dpi. Consequently,
the matrix size to be developed is 2 (lateral).times.2 (vertical).
As illustrated, a pattern to be developed by 4-bit data ("0000",
"0001", "0010", "0011", "0100") for 5 gradation values is set
beforehand for the same. This setting pattern may be held in the
ROM of the printer, or, downloaded from the host device together
with the image data. 4-bit data of 600 dpi are developed by pixel
unit based on the pattern of respective graduation level sets as
mentioned above, to generate 1-bit (2 gradation values) data of
1200 dpi In the print engine control section 220 preliminary
ejection data are added as paper preliminary ejection generated
beforehand as described later by OR (logical sum) to the data of
1-bit (2 gradation values) for respective colors of thus developed
K, LC, LM, C, M, Y.
FIG. 7 is a diagram showing printing data of the paper preliminary
ejection to be added through a data pattern arranged in the
pixel.
The pattern of this FIG. 7 shows a basic pattern for an ink of one
color. More specifically, as described after with reference to FIG.
8 and subsequent drawings, the paper preliminary ejection is not
performed for all kinds of inks used in the printing apparatus of
the embodiment but is performed for the kind of ink in which the
ejection failure occurs due to viscosity of ink increased during a
predetermined time period at which the normal preliminary ejection
is performed. It should be appreciated that the number of ejection
orifices in the printing head is set to 16, less than the reality,
to simplify the description and reference signs 310 to 325 of the
printing head 22 represent 16 respective ejection orifices.
Further, the resolution of the paper preliminary ejection pattern
is equal to that of the binary data and, in the present embodiment,
the resolution in Y direction is supposed to be 1200 dpi, equal to
the resolution of the printing head, and also 1200 dpi in X
direction. Reference numeral 360 represents the original point (X0,
Y0) of the target pixel. In the case of forming an additional dot
of preliminary ejection to this target pixel, ink ejection from an
ejection orifice 310 will be applied. The pixel of coordinates
(X0+X1, 1) gained by shifting by X1 pixels in the X direction and 1
pixel in the Y direction from the original point 360 is a target
pixel 361 to which ink from the ejection orifice 311 is applied.
Similarly, the pixel of coordinate (X0+2.times.X1, 2) gained by
shifting by X1 pixels in the X direction and 1 pixel in the Y
direction from the target pixel 361 to which ink is added by the
ejection orifice 311 is a target pixel 362 to which ink from the
ejection orifice 312 is applied. Further, the pixel of coordinate
(X0+3.times.X1, 3) gained by shifting by X1 pixels in the X
direction and 1 pixel in the Y direction from the target pixel 362
is a target pixel 363 to which ink from the ejection orifice 313 is
applied. In the pattern, when becoming Y0+3=Y1-1, the target pixel
364 to which ink from the ejection orifice 314 is added is repeated
as (X0+X1, Y1). Thus, pixels in which ink is ejected for
preliminary ejection can be determined all over the printing area,
by repeating a paper preliminary ejection pattern of a size of
4.times.X1 pixels in the X direction and 4.times.Y1 pixels, which
is a pattern unit for performing paper preliminary ejection to all
of 16 ejection orifices, for the ink of one color.
In the case where the paper preliminary ejection is performed for
plurality kinds of ink, the pattern of paper preliminary ejection
for them can be described with four parameters of original point
X0, Y0, distances X1 and Y1 between dots, for each color.
Obviously, the aforementioned pattern of paper preliminary ejection
is an example, parameters of other forms may also be used for
realizing other patterns of paper preliminary ejection, and, a
pattern may be expressed without using parameters.
First Embodiment
The first embodiment of the present invention is set to perform the
paper preliminary ejection for only cyan ink out of cyan, magenta,
yellow, black, light cyan and light magenta. More specifically, the
present embodiment is set to perform so-called normal preliminary
ejection, in which preliminary ejection is executed into an ink
receptacle in the vicinity of the home position for each reciprocal
scanning of a printing head. In this case, as mentioned below, if
it is set to perform the normal preliminary ejection for each
reciprocal scanning, there may be a color of ink which may possibly
cause ejection failure due to increased viscosity if no ejection is
executed during reciprocal scanning. In the present embodiment the
cyan ink corresponds to that ink. Therefore, the paper preliminary
ejection is executed only for this cyan ink. In other words, the
number of colors of ink that require execution of the paper
preliminary ejection may possibly increase, in an apparatus where
the interval for executing the aforementioned normal preliminary
ejection is set longer, and in such a case, it goes without saying
that the paper preliminary ejection is to be also executed
according to the present invention for those colors of ink. Thus,
the application of the present embodiment is relative with respect
to the interval for executing normal preliminary ejection, and ink
requiring the paper preliminary ejection is determined according to
that interval.
FIG. 8 shows the printing operation of the present embodiment along
a time axis. In the present embodiment, a carriage 11 (refer to
FIG. 1) moves at a speed of 12 inch/sec for scanning of the
printing head performed and the printing is executed through the
bidirectional scanning thereof. Then, the printing head is moved to
the ink receptacle in the vicinity of the home position each time a
single reciprocal scanning is completed so as to perform the normal
preliminary ejection. As shown in FIG. 8, one cycle of printing
operation comprises, after the normal preliminary ejection, (1)
printing in a forward direction, (2) change of scanning direction,
(3) printing in a backward direction and (4) normal preliminary
ejection, all of which are performed on time, and printing of a
predetermined amount such as a page is carried out by repeating
them. It should be appreciated that a predetermined printing start
operation is performed when printing of this predetermined amount
is started. This printing start operation includes an operation for
ejecting ink from the printing head such as normal preliminary
ejection or suction processing. In the above printing operation, as
shown in FIG. 8, the time interval from the execution of the normal
preliminary ejection or printing start operation to the execution
of the next preliminary ejection is set to 1.6 sec. In short, it is
so composed to execute the normal preliminary ejection per one
cycle of reciprocal scanning, through the design of the printer of
the present embodiment.
Here, it is intended to define the longest period of time (also
called "rest time" hereinafter) that enables maintaining the state
where image data showing "non-ejection" continues from scanning
after the normal preliminary ejection, and thereafter no ejection
failure occurs in the ink ejection of the first image data showing
"ejection" and to then use this time to evaluate the presence or
absence of the paper preliminary ejection or the frequency of the
paper preliminary ejection. Here, the state where any ejection
failure does not occur designates a state where non-ejection
phenomenon where ink is not ejected from the nozzle, distortion
phenomenon where ink is ejected though not quite satisfactorily but
the landing position of this ejected ink is deviated from the
regular position, splashing ejection phenomenon due to insufficient
ink refill, and so on do not occur.
It should be appreciated that the rest time as defined above varies
according to the presence or absence of the paper preliminary
ejection or the frequency thereof as shown in Table 1 below, and
the rest time becomes longer in the case where the paper
preliminary ejection is performed in comparison to the case where
paper preliminary ejection is not performed.
The definition of rest time can apply to the case of not performing
the paper preliminary ejection or the case of performing the paper
preliminary ejection. First, the rest time in the case of not
performing the paper preliminary ejection shall be described
referring to the example of cyan in Table 1. Here, a rest time of
1.1 sec means that no ejection failure occurs in the first
ejection, if the non-ejection period after the normal preliminary
ejection is shorter than 1.1 sec. In other words, ejection failure
occurs if the non-ejection period from the normal preliminary
ejection is equal to or longer than 1.1 sec.
Also, the rest time can be explained as follows when the paper
preliminary ejection is executed. In general, the frequency of the
paper preliminary ejection is set to be a value lower than the
frequency of ink ejection during printing or normal preliminary
ejection, so that ink dots on the printing medium through the paper
preliminary erection are unremarkable in contrast to the printed
image. Therefore, ejection failure may sometimes occur according to
the kind of ink even if the paper preliminary ejection is simply
executed at a given constant cycle. A rest time of 2.7 sec for cyan
in Table 1 means that ejection failure occurs if the non-ejection
period is equal to or longer than 2.7 sec even if the paper
preliminary ejection is executed by one time of ejection/8 inch. In
other words, it comes off without producing ejection failure if the
non-ejection period from the normal preliminary ejection is shorter
than 2.7 sec. According to this, the time of keeping a better
printing state becomes longer comparing to the case without paper
preliminary ejection. Thus, it is advantageous in increasing
quality of a printed image.
TABLE-US-00001 TABLE 1 Rest time [s] Light Light Cyan Magenta
Yellow Cyan Magenta Without paper 1.1 9.2 2.8 12.3 or 12.3 or
preliminary longer longer ejection With one time 2.7 12.3 or 12.3
or 12.3 or 12.3 or of paper longer longer longer longer preliminary
ejection per 8 inch With one time 2.7 12.3 or 12.3 or 12.3 or 12.3
or of paper longer longer longer longer preliminary ejection per 4
inch
Table 1 shows the rest time according to the presence or absence of
the paper preliminary ejection and the frequency of paper
preliminary ejection in the case of ejecting respective ink of
black, light cyan, cyan, light magenta, magenta and yellow from the
ejection orifice 23 of respective printing heads 22K, 22LC, 22C,
22LM, 22M and 22Y (refer to FIG. 1). It should be appreciated that
the description of black ink is omitted in Table 1.
As it is evident from Table 1, the rest time of cyan ink in the
case of not performing the paper preliminary ejection is 1.1 sec,
which is shorter than the time of 1.6 sec from the normal
preliminary ejection to the next normal preliminary ejection, shown
in FIG. 8. Consequently, the printing head 22C for ejecting cyan
ink generates election failure to degrade the printing quality if
the printing starts at a time point longer than 1.1 sec, for
instance at the time point of 1.5 sec, within 1.6 sec corresponding
to the printing time by the aforementioned reciprocal scanning.
Therefore, the predetermined paper preliminary ejection shall be
performed only for the printing head 22C of cyan ink. This paper
preliminary ejection makes the rest time concerning the cyan ink
2.7 sec, preventing the ejection failure from occurring, even if
the printing starts within 1.6 sec corresponding to one time
interval between consecutive two times of normal preliminary
ejection.
In other words, as it is evident from Table 1, with regard to the
rest time in the case of not performing the paper preliminary
ejection, only cyan ink has the time shorter than 1.6 sec (the
black ink of the present embodiment also has the time longer than
1.6 sec similarly to the other ink), so the paper preliminary
ejection shall be performed only for the printing head of this ink.
Thereby, the paper preliminary ejection is not executed for the
other ink, avoiding unnecessary ink consumption provoked by uniform
paper preliminary ejection for all colors of ink.
Here, the frequency of paper preliminary ejection for determining
the rest time shown in Table 1 above is one time of ejection/8 inch
(hence, 1.5 times ejections/sec=3 times ejections/2 sec) and one
time ejection/4 inch (similarly, 3 times ejections/sec=6 times
ejections/2 sec). It should be appreciated that only one time of
paper preliminary ejection based on the pattern shown in FIG. 7 may
well be performed per 8 inch in the main scanning direction, if the
paper preliminary ejection shall be executed by one time ejection/8
inch. And, only one time of paper preliminary ejection based on the
pattern shown in FIG. 7 may well be performed per 4 inch in the
main scanning direction, if the paper preliminary ejection shall be
executed by one time ejection/4 inch. It should be appreciated that
the rest time for the cyan ink in the present embodiment is not
different between that in the case where the frequency of paper
preliminary ejection is one time ejection/8 inch and that in the
case of one time ejection/4 inch. This is mainly due to the
property of the ink which relatively tends to increase the
viscosity, and thus, the rest time does not increase for such ink
even if the frequency of paper preliminary ejection increases. The
present embodiment adopts a lower frequency of one time ejection/8
inch for the paper preliminary ejection of cyan ink, so that dots
by the same may not be remarkable. It goes without saying that,
though the frequency of paper preliminary ejection is shown for one
time ejection/8 inch and one time ejection /4 inch, the ejection
frequency is not limited to the same. This ejection frequency can
be fixed within a range of not highlighting ink dots of preliminary
ejection formed on a printing medium.
Second Embodiment
A second embodiment of the present embodiment is a case where there
are a plurality of colors of ink requiring the paper preliminary
ejection and the frequency of paper preliminary ejection is
different depending on these colors of ink.
TABLE-US-00002 TABLE 2 Rest time [s] Light Light Cyan Magenta
Yellow Cyan Magenta Without paper 1.1 1.5 1.3 12.3 or 12.3 or
preliminary longer longer ejection With one time 1.5 2.7 12.3 or
12.3 or 12.3 or of paper longer longer longer preliminary ejection
per 8 inch With one time 2.7 12.3 or 12.3 or 12.3 or 12.3 or of
paper longer longer longer longer preliminary ejection per 4
inch
Table 2 shows the rest time according to the presence or absence of
paper preliminary ejection and the frequency of paper preliminary
ejection, for the present embodiment. As shown in Table 2, the rest
time in the case of not performing the paper preliminary ejection
is 1.1 sec for cyan ink, 1.5 sec for magenta ink and 1.3 sec for
yellow ink, which are shorter than the time interval of 1.6 sec,
corresponding to the time interval between consecutive two times of
normal preliminary ejection, shown in FIG. 8, for these colors of
ink. Therefore, it becomes necessary to perform the paper
preliminary ejection. However, for the cyan ink, the rest time is
1.5 sec for the paper preliminary ejection of the frequency of one
time ejection/8 inch, and ejection failure may occur if the
printing starts after 1.5 sec within the time interval of 1.6 sec.
Consequently, the paper preliminary ejection of the frequency of
one time ejection/4 inch is performed for cyan ink, and the paper
preliminary ejection of the frequency of one time ejection/8 inch
is performed for magenta and yellow ink. Thereby, the rest time
becomes not shorter than 1.6 sec for any ink, and ejection failure
will not occur even if the printing starts in one time interval of
consecutive two times of normal preliminary ejection, namely, 1.6
sec corresponding to the time of reciprocal scanning. Also, the
paper preliminary ejection is performed at the required minimum
frequency according to the color of ink, avoiding unnecessary
execution of the paper preliminary ejection at high frequency, and
limiting the amount of ink to be consumed by the paper preliminary
ejection.
Third Embodiment
A third embodiment of the present invention relates to the
application of the paper preliminary ejection to a case of using a
printing head that can eject two kinds of ejection amount (volume
of ink drop) for a single color of ink.
The above first embodiment corresponds to a case where the volume
(ejection amount) of one ink drop ejected from respective ejection
orifices is 4 pl. On the contrary, the present embodiment uses a
printing head provided with two kinds of ejection orifices for
ejecting 4 pl and 8 pl.
FIG. 9 shows the ejection orifice arrangement of respective ink
colors of such a printing head. As shown in the drawing, an
ejection orifice 1202 of 8 pl in ejection amount and an ejection
orifice 1203 of 4 pl in ejection amount are arranged respectively
in printing heads 1201K, 1201LC, 1201C, 1201LM, 1201M, 1201Y of
respective colors of ink.
TABLE-US-00003 TABLE 3 Rest time [s] Light Light Cyan Magenta
Yellow Cyan Magenta 4pl Without 1.1 9.2 2.8 12. 3 or 12.3 or paper
longer longer preliminary ejection With one 2.7 12.3 or 12.3 or
12.3 or 12.3 or time of longer longer longer longer paper
preliminary ejection per 8 inch 8pl With one 3.4 6.2 3.6 4.9 4.1
time of paper preliminary ejection per 4 inch
Table 3 shows the rest time according to the presence or absence of
paper preliminary ejection and the frequency of paper preliminary
ejection, for each ejection quantity, concerning the present
embodiment.
As shown in Table 3, a case where ejection failure may occur if
printing starts within time period of 1.6 sec shown in FIG. 8 is a
case where ink of ejection amount 4 pl is ejected for cyan ink.
Therefore, the present embodiment executes the paper preliminary
ejection only from the ejection orifices of ejection amount 4 pl at
a frequency of one time ejection per 8 inch. Thus, the paper
preliminary ejection is performed only for the ejection orifices
according to the ejection amount of respective ink colors, and then
unnecessary paper preliminary ejection is prevented to decrease the
ink amount used for the paper preliminary ejection.
Other Embodiments
Though, in the aforementioned respective embodiments, a binary
paper preliminary ejection pattern is added to the binarized
printing data after the index development, data of the paper
preliminary ejection pattern may be added to the printing data of
index form.
FIG. 10 is a block diagram showing a data processing in the host
device 200 and the printer 240, in the case of adding preliminary
ejection data of index form, and a similar one to FIG. 5 mentioned
above. In short, a similar processing is performed up to the
quantization processing 520 of the data transferred from the host
device 200 by the printer 240.
A processing 540 for adding a paper preliminary ejection pattern is
executed to 4-bit (5 gradation values) data of quantized K, LC, LM,
C, M, Y. More specifically, the 4-bit (5 gradation values) data of
quantized K, LC, LM, C, M, Y have any one value among "0000",
"0001", "0010", "0011", "0100" as described in FIG. 6. If it has
the value of "0001", "0010", "0011", "0100", the paper preliminary
ejection data are not added, because ink is ejected to the pixel.
On the other hand, in the case of "0000", paper preliminary
ejection data as shown in FIG. 12 are added.
Then, the printing data to which the preliminary ejection data are
added are converted into printing data of 1-bit (2 gradation
values) for respective colors of K, LC, LM, C, M, Y and transferred
to the printer engine 220 as printing data containing the paper
preliminary ejection data.
FIG. 11 is a diagram illustrating an index development pattern used
for the preliminary ejection. As shown in the same drawing, two
kinds of patterns as shown by pattern 900 and pattern 910 are
prepared, as an index development pattern corresponding to 4-bit
data of "0001" used as paper preliminary ejection data. It becomes
possible to prevent the deflection of the ejection orifice to
perform the paper preliminary ejection, by using these two kinds of
patterns alternatively.
In addition, the present invention can also be applied to a
composition for performing image processing in a printer driver of
the host device. FIG. 12, similar to FIG. 4, shows an example of
the composition. In this case, it is unnecessary to equip the
printer with an image controller for assuming mainly image
processing, thereby reducing the cost of the printer.
In this composition, the printing operation starts by sending image
data from the host device 200 to a reception buffer 250 of a print
engine control section 220. The print engine control section 220
analyzes the image data received from the host device 200 and
generates information necessary for the printing such as printing
data, printing quality, and margin information. There, printing
data, printing quality, margin information or the like are
processed by an MPU 221 through an ASIC 222 and held in a RAM 228.
Thereafter, this information is referred to as necessary and used
for segmenting the process. Furthermore, the mask pattern is
written in a mask buffer 230 as necessary. And, printing data to
which the data of paper preliminary ejection are added can be
created by taking the OR (logical sum) of preliminary ejection data
which are preliminary generated and the above, as printing
data.
The present invention has been described in detail with respect to
preferred embodiments, and it will now be apparent from the
foregoing to those skilled in the art that changes and
modifications may be made without departing from the invention in
its broader aspects, and it is the intention, therefore that the
appended claims cover all such changes and modifications as fall
within the true spirit of the invention.
This application claims priority from Japanese Patent Application
No. 2004-177374 filed Jun. 15, 2004, which is hereby incorporated
by reference herein.
* * * * *